JPS63241842A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To completely remove the deflection aberration and obtain high resolution over the whole area of a screen surface by forming nonrotating symmetrical lenses and applying the voltage increasing in response to the electron beam deflection quantity in grids made of three members. CONSTITUTION:An electron beam from a cathode 1 is focused by a sub-lens formed between grids G4, G35, G6 and a main lens formed by G6, G7 and hits the surface of a fluorescent screen. G35 is provided with three members, the members 38, 40 have circular electron beam passing holes 41, 41 and a horizontally long groove hole 42 on the mating face with the member 39, and the member 39 has a vertically long electron beam passing hole 43. The fixed voltage is applied to the member 39 so as to form a nonrotating symmetrical lens in whlch the ratio between the vertical diameter and the horizontal diameter of the electron beam cross section outgoing from G35 is made larger than that of the electron beam cross section incoming to G35. The voltage increasing in response to an increase of the electron beam deflection quantity is applied to the members 38, 40.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a color cathode ray tube, and particularly to an electron gun thereof.

(Prior Art) In general, color cathode ray tubes are mainly based on an in-line electron gun system in which three electron guns are arranged in a row.

The reason for the deterioration of the resolution characteristics of this in-line electron gun type color cathode ray tube is that when the electron beam is deflected from the center of the phosphor screen surface to the periphery, the beam spot on the phosphor screen surface becomes large. There is a deflection aberration. This deflection aberration consists of a superposition of two different deflection aberrations.

One is that the electron beam trajectory from the electron gun to the phosphor screen surface becomes elongated as the electron beam radius increases, resulting in a small-diameter, perfectly circular beam at the center of the phosphor screen surface. Even if the focus voltage is maintained at the optimum focus voltage that allows a spot to be obtained, the deflection aberration causes the beam pot to be in an over-focus state at the periphery of the phosphor screen surface.

(Hereinafter, this will be referred to as the first deflection aberration.) The other is the deflection aberration caused by the non-uniformity of the deflection magnetic field. That is, in an in-line electron gun type color cathode ray tube, the horizontal deflection magnetic field is shaped like a bottle cushion as shown in Figure 4 (2), and the vertical deflection magnetic field is distorted into a barrel shape as shown in Figure 4 (0). By creating a magnetic field, the three electron beams (21), (22), and (23) are self-converged. The electron beam that has passed through this non-uniform magnetic field is diverging in the horizontal direction and converging in the vertical direction, resulting in a long, flat cross-sectional shape in the horizontal direction, and a non-circular shape, especially at the periphery of the phosphor screen surface. This results in a distorted beam spot.

(Hereinafter, this will be referred to as the second deflection aberration.) FIG. 5 shows the trajectory of the electron beam in a state where the two deflection aberrations are superimposed. When the optimum focus voltage is maintained at the center of the phosphor screen surface, when the electron beam is deflected toward the periphery of the phosphor screen surface, the horizontal divergence effect on the electron beam due to the non-uniform deflection magnetic field will be reduced. is the phosphor screen surface (
(to) becomes under-focused. For this reason, it acts in the direction of reducing overfocus of the beam spot due to the elongation of the electron beam trajectory as the Kasushi beam deflection increases. Therefore, the horizontal convergence plane (to) of the electron beam is formed at a position slightly inside from the phosphor screen surface (to), resulting in slight overfocus. On the other hand, the vertical convergence effect acts to make the beam spot more overfocused. Therefore, the vertical convergence surface (2) of the electron beam is located roughly inside the horizontal convergence surface (to), resulting in significant overfocus. As a result,
While the beam spot generated at the center of the phosphor screen is a perfect circle as shown in Figure 6 (24),
The beam spot generated at the periphery is distorted into a non-circular shape consisting of a high-brightness core part (26) and a low-brightness halo part (27), as shown in FIG. 6 (25), and the phosphor screen The resolution at the periphery of the surface deteriorates significantly.

As a means for correcting the distortion of the beam spot shape in the peripheral area of the phosphor screen surface, Japanese Patent Laid-Open No. 61-742
The technology shown in Publication No. 46@ is proposed, that is,
As shown in FIG. 7, the cathode ■, the first grid ■, the second grid (3), the third grid (A), the fourth grid ■,
In a quadra potential electron gun consisting of a fifth grid (2) and a sixth grid (2), the fourth grid θG is composed of three members: a first member (2), a second member (9), and a third member 0Φ. The first member (8) and the third member 0Φ have three circular electron beam passing holes, and the second member 0 has a horizontally long rectangular electron beam passing hole. There is. A constant voltage v2 is applied to the first member (8) and the third member 0Φ, and a dynamic voltage VD that changes depending on the amount of deflection of the electron beam is applied to the second member 0.
Apply. The dynamite voltage VD takes the same value as the voltage V2 when the electron beam deflection stage is zero, and gradually decreases from the voltage V2 as the amount of deflection increases. Therefore, the three members (8), (9), and Q that constitute the fourth grid are formed only when the electron beam is deflected.
A rotationally symmetric lens of Φ is constructed.

According to the technique disclosed in the above publication, the non-rotationally symmetrical lens has a strong focusing effect in the vertical direction and a weak focusing effect in the horizontal direction on the electron beam passing through it, so that the fifth grid (2) and the sixth grid The electron beam that enters the main lens formed between (2) and (2) has a cross-sectional shape that is polarized into a horizontally long ellipse. As can be easily seen from the electrode shape in FIG. 7, in order to achieve such a non-rotationally symmetrical lens effect, it is necessary that the dynamic voltage Volt decrease as the voltage increases. Dynamic voltage VD
This decrease strengthens the unipotential lens formed by the third to fifth grids, and the electron beam becomes strongly overfocused at the periphery of the phosphor screen surface. That is, the electrode shape shown in FIG. 7 inevitably causes an increase in the first deflection aberration mentioned above, and rather deteriorates the scum in the peripheral area of the phosphor screen surface. Roughly speaking, when the electron beam with the elliptical cross section is incident on the main lens, the spherical aberration of the lens causes a focusing effect that is strong in the horizontal direction and weak in the vertical direction. It acts to cancel out the horizontal divergence effect and vertical convergence effect on the As a result, the aforementioned deflection aberration is reduced, and it is possible to suppress deterioration of resolution in the peripheral area of the phosphor screen surface.

However, as described in the above-mentioned publication, when the vertical convergence effect of the non-rotationally symmetric lens is made stronger than the horizontal convergence effect, the beam spot becomes more overfocused in the vertical direction and is deflected. The aberration cannot be canceled out, but on the contrary acts in the direction of increasing the second deflection aberration as well. As a result, the resolution of the periphery of the phosphor screen surface deteriorates considerably.

Contrary to the proposal in the above publication, the voltage applied to the second member (2) of the fourth grid is a dynamic voltage VD, and the voltage (29) changes in synchronization with the deflection current (28) as shown in FIG. , that is, at the time of quiet zero deflection, the voltage v
By setting the voltage to have the same value as V2 and gradually increase from voltage V2 as the amount of deflection increases, deflection aberration can be reduced. FIG. 8 shows the trajectory of the electron beam in this state. That is, when the electron beam is deflected, the three members (c) of the fourth grid are 0,00
A non-rotationally symmetric lens 0Φ is formed in between. On the other hand, a rotationally symmetrical lens (b) is provided between the third grid) and the first member (c) of the fourth grid, and between the third member 0Φ of the fourth grid and the fifth grid (b). is formed. The rotationally non-rotationally symmetrical lens CΦ exerts a weak convergence effect on the electron beam in the horizontal direction and a divergence effect in the vertical direction. Therefore, the electron beam that has passed through the rotationally asymmetric lens OΦ has an elliptical cross-sectional shape that is elongated in the vertical direction.

The vertical diverging effect acts so that the beam spot becomes underfocused on the phosphor screen surface, so it cancels out the overfocusing of the beam spot in the vertical direction due to the second deflection aberration mentioned above. Can be done. Therefore, the vertical convergence surface (1) of the electron beam can be brought closer than the phosphor screen surface (to).

On the other hand, the weak convergence effect in the horizontal direction acts to slightly overfocus the beam spot, so
The horizontal converging surface (a) moves further from the phosphor screen surface (to) toward the electron gun. As a result, as shown in FIG.
Therefore, deflection aberration can be reduced.

However, even in this case, as shown in Figure 8, if the horizontal convergence plane (to) and the vertical convergence plane (■) of the electron beam at the periphery of the phosphor screen surface (to) coincide with each other, Since the converging surface is located closer to the electron gun than the phosphor screen surface, the beam spot is overfocused in both the horizontal and vertical directions, but the beam spot diameter is not the minimum. This is because the non-rotationally symmetric lens 0ftl is much weaker than the rotationally symmetric lens (b), and if the aforementioned second deflection aberration is moderately compensated, the first deflection aberration is insufficiently compensated. To become.

Therefore, the improvement in resolution at the periphery of the phosphor screen surface is insufficient. In order to roughly improve the resolution with this method, for example, as the amount of deflection increases, the voltage of the front 2nd and 5th grid 0 is increased, the convergence effect of the main lens 00 is weakened, and the 21st deflection aberration is strongly compensated for. It is necessary to use a so-called dynamic focus method. However, this increases the cost of the color cathode ray tube drive device because the voltage modulation circuit requires something other than the dynamic voltage VD, and moreover, the dynamic focus circuit requires at least a withstand voltage correction for the reference voltage. becomes.

(Problems to be Solved by the Invention) As described above, even if the horizontal and vertical convergence planes are made to coincide, they are located closer to the electron gun than the phosphor screen surface. The resolution must be improved, and there are problems such as an increase in cost in order to improve the resolution.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and its object is to provide a color cathode ray tube that can obtain high resolution over the entire phosphor screen surface.

[Structure of the invention]

(Means for solving the problem) A color cathode ray tube equipped with an in-line electron gun consisting of a cathode, a first grid, a second grid, a third grid, a fourth grid, a fifth grid, and a sixth grid. The grid is divided into three parts in the tube axis direction into a first member, a second member, and a third member, and the ratio of the vertical diameter to the horizontal diameter of the cross section of the electron beam emitted from the fourth grid is the fourth member. A constant voltage is applied to the second member, and a constant voltage is applied to the first member and the third member so as to form a non-rotationally symmetric lens that is larger than the vertical diameter of the cross section of the electron beam incident on the grid. This is a color cathode ray tube to which a voltage that increases as the electron beam deflection increases is applied.

The first and third members of the fourth grid are circular electron beam passing holes, and the surface of the fourth grid facing the second member is provided with one horizontally long slot. The second member may be a vertically elongated electron beam passage hole.

The first member and the third member of the fourth grid may be circular electron beam passing holes, and the second member of the fourth grid may be a vertically elongated electron beam passing hole.

The first member and the third member of the fourth grid are circular electron beam passing holes, and the surface facing the second member of the fourth grid is one horizontally long slot, and the fourth grid The second member may be a circular electron beam passage hole.

(Function) According to the present invention, it is possible to completely eliminate deflection aberration in a color cathode ray tube, and to significantly improve resolution deterioration in the peripheral area of the phosphor screen surface.

(Example) Hereinafter, an example of the present invention will be specifically described using the drawings.

FIG. 1 is a perspective view showing a schematic configuration of an inline-arranged quadra potential type color cathode ray tube electron gun, which is an embodiment of the present invention, and FIGS. FIG. Cathode■
The deuteron beam emitted from the third grid), the fourth grid
The light is focused by the grid (35), the sub-lens formed between the fifth grid ①, and the main lens formed between the fifth grid 0 and the sixth grid ① onto the phosphor screen surface (not shown). To shoot. The fourth grid (35) consists of three members, the first member (38)
and the third member (40) has a circular electron beam passage hole.
(41), and a horizontally long slot (42) on the surface facing the second member (39). Also, the second
The member (39) has a vertically long electron beam passage hole (43).
).

Typical DC ground potentials applied to each electrode during operation are as follows: cathode Q) 50 to 150V, first grid Ov1 second grid (3) Boo to 800V, third grid (a) and fifth grid The grid voltage is 08 kV (VF), the sixth grid ■ is 27 kV (Va), and the second member (39) of the fourth grid (35) is marked with the same DC potential of 600 to 800 V (V2) as the second grid ■. It's called out.

A dynamic voltage VD (29) that changes in synchronization with the deflection current (28) as shown in FIG. 9 is applied to the first member (38) and the third member (40). The trajectory of the electron beam in this case is shown in FIG. The dynamic voltage V
o (29) is v when the electron beam deflection table is in the atmosphere.
2, the three members of the fourth grid (3
8), (39), (40), the non-rotationally symmetrical lens 0e is not formed between the third grid) and the first member (38) of the fourth grid, and the third member of the fourth grid. A rotationally symmetrical sub-lens (b) is formed between (40) and the fifth grid 0. When electrons are deflected, the dynamic voltage Vp (29) has a value higher than v2, and increases as the amount of deflection increases. Therefore, the three members (38), (39) of the fourth grid
, (40), a rotationally non-rotationally symmetrical lens is formed, and the convergence effect of the rotationally symmetrical sub-lens (b) is weakened. The non-rotationally symmetrical lens 08 acts so that the cross-sectional shape of the electron beam becomes an ellipse that is elongated in the vertical direction. Therefore, the horizontal convergence plane (to) and the vertical convergence plane (a) of the electron beam can be made to coincide (second
(deflection aberration compensation effect). Roughly speaking, since the rotationally symmetrical sub-lens (b) is weakened, it is simultaneously underfocused in the horizontal and vertical directions, and the converging surface in both directions moves toward the phosphor screen surface.

As a result, both the horizontal and vertical focusing surfaces can be aligned with the phosphor screen surface at the same time (
(first deflection aberration compensation action). In the case of this embodiment, since the electron beam intensity of the sub-lens (b) shown in FIG. 3 is strong, this first deflection aberration compensation effect can be sufficiently strong. Therefore, both the first and second deflection aberration compensation functions can be optimized using only one dynamic voltage VD. As a result, the deflection aberration at the periphery of the phosphor screen surface is completely eliminated and the beam spot is minimized, so that the resolution at the periphery can be significantly improved.

According to experiments, the optimum value of the dynamic voltage VD when deflecting the electron beam to the diagonal periphery of the phosphor screen surface is determined by the directivity 'F' applied to the second member of the fourth grid.
, the voltage was approximately 500V based on voltage (2). On the other hand, since the DC voltage V2G is t600 to 800V, the maximum value of the dynamic voltage VD is relatively low, about 1300V or less, so there is no need to take any special consideration to the voltage supply configuration, and therefore Highly reliable.

Furthermore, the effects of the present invention can also be satisfied with the following configuration. As shown in FIG. 10, the first member (4
8) and the third member (50) have a circular electron beam passage hole (51), and the second member (49) has a vertically long electron beam passage hole (53). In this case also before)′
Similarly to the eleventh embodiment, a dynamic voltage VD ( shown in FIG. 9) is applied to the first member (48) and the third member (50).
29) and apply a constant voltage v2 to the second member (49).

Further, as shown in FIG. 11, the first member (58) and the third member (60) of the fourth grid are horizontal to the opposite surface of the second member (59) together with the circular electron beam passage hole (61). The same applies to a configuration in which the second member (59) has a slot (62) long in the direction and a circular electron beam passage hole (61) in the second member (59).

Note that in this embodiment, the voltage v2 applied to the second member (59) of the fourth grid is the same as the voltage applied to the second grid (2), but the present invention is not limited to this; A similar effect can be obtained using voltage.

〔Effect of the invention〕

Since the present invention is configured as described above, deflection aberrations are caused by the nonuniformity of the deflection magnetic field, and by the elongation of the trajectory of the electron beam from the electron gun to the phosphor screen surface due to the increase in the number of deflection tables. The pot aberrations caused by the phosphor screen can be eliminated by applying one type of relatively low dynamic voltage, and good resolution can be obtained over the entire phosphor screen surface.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an electron gun for a color cathode ray tube according to the present invention, FIG. Figure 4 (9) is a diagram explaining the trajectory of the electron beam in the tube, υ is a schematic diagram showing the horizontal and vertical deflection magnetic field distribution, and Figure 5 is the beam trajectory to explain the deflection aberration created in a color cathode ray tube. Figure 6 is a schematic diagram for explaining the beam spot shape on the phosphor screen surface, Figure 7 is an exploded perspective view of a conventional color cathode ray tube electron gun, and Figure 8 is a conventional color cathode ray tube. FIG. 9 is a signal waveform diagram showing the relationship between deflection current and dynamic voltage. FIGS. 10 and 11 are diagrams showing the main parts of an electron gun according to an embodiment of the present invention. FIG. 3 is a perspective view showing an electrode configuration. (1)...Cathode (2)...First grid (3)...Second grid (4)...
...3rd grid (4)...4th grid
(6)...5th grid (7)...6th grid (8), (38), (4B), (58)...
...first member (9), (39), (49),
(59)... Second member (10), (40),
(50), (60)...Third member agent
Patent Attorney Norio Chika Yudo Norio Ogo Figure 7 Figure 8

Claims (4)

[Claims] (1) At least a cathode, a first grid, a second grid,
3rd grid, 4th grid, 5th grid and 6th grid
In a color cathode ray tube equipped with an in-line electron gun consisting of a grid, the fourth grid is divided into three parts in the tube axis direction into a first member, a second member, and a third member, and the electron beam is emitted from the fourth grid. to form a non-rotationally symmetric lens in which the ratio of the vertical diameter to the horizontal diameter of the electron beam cross section incident on the fourth grid is larger than the ratio of the vertical diameter to the horizontal diameter of the electron beam cross section incident on the fourth grid. , said second
A constant voltage is applied to the members, and the first member and the third member
A color cathode ray tube characterized in that a voltage that increases as the amount of electron beam deflection increases is applied to the member. (2) The first member and the third member of the fourth grid have circular electron beam passing holes, and at least one horizontally long slot on the surface facing the second member of the fourth grid. 2. The color cathode ray tube according to claim 1, wherein the second member of the fourth grid has a vertically long electron beam passage hole. (3) The first member and the third member of the fourth grid are
2. The color cathode ray tube according to claim 1, wherein the second member of the fourth grid has a circular electron beam passage hole, and the second member of the fourth grid has a vertically elongated electron beam passage hole. (4) The first member and the third member of the fourth grid are
The second member of the fourth grid has a circular electron beam passage hole and at least one horizontally long slot on the surface facing the second member of the fourth grid, and the fourth grid has a circular electron beam passage hole. A color cathode ray tube according to claim 1, which has holes.